The present invention relates to a fastening or connecting element for ceramic components.
Ceramic materials and especially fiber-reinforced ceramic materials belong to the group of most important materials for technical developments in space applications due to their high temperature resistance combined with a very low specific weight.
Presently, a plurality of structural components for thermal protection, rocket propulsion systems etc. are produced from these materials. Larger components are produced for reasons of technical simplicity and economic considerations from individual parts according to the principle of separation and combination. For connecting such components fastening elements are necessary. Their general importance becomes obvious when one considers that they are, according to their application, the most important and most ubiquitous structural element overall. Threaded connections are traditionally of a great importance in machine construction, aerospace construction, and in many other technical fields.
The methods for subsequently connecting parts must be simple and economical, but also provide elements that are structurally compatible with the parts to be connected so that their load capacity and their limits with respect to applications, for example, with respect to temperature ranges, are not impeded. However, this is not possible with fastening elements of conventional materials, for example, metallic materials. Even though metallic fastening elements have in general advantageous properties, they are essentially not suitable for connecting ceramic components. Their substantially greater heat expansion coefficient, their tendency to flow, and the relatively low load capacity at temperatures that are still relatively low with respect to the temperature range of ceramic materials as well as their oxidation sensitivity result in the fact that metallic fastening elements can be used at high temperatures only to a small extent. Already at temperatures of use of up to 1600.degree. C., which are typical for fiber-reinforced ceramic materials, metallic screws can no longer be used.
It is therefore an object of the present invention to provide a fastening element of the aforementioned kind for ceramic components that are exposed to high temperatures.